1. Field of the Invention
The present invention relates to a container, and more particularly to a thermal flask with a vacuum solar heating device that can heat liquid in the flask by solar energy.
2. Description of Related Art
A thermal flask is a container that can be used to carry liquid. Flasks are vacuum-insulated to keep the liquid hot or cold for a long period of time. However, conventional flasks can only keep a liquid hot to the drink but cannot heat the liquid while traveling. The temperature of the liquid in the flask will gradually approach ambient temperature, and the heat preserving effect of the flask cannot be maintained for a desired extremely long time.
To overcome the shortcoming, the present invention provides a thermal flask with a vacuum solar heating device to mitigate or obviate the aforementioned problem, and utilizes the free and clean solar power.
The main objective of the invention is to provide a thermal flask with a vacuum solar heating device to heat the liquid by solar energy. The thermal flask in accordance with the present invention has a hollow body and a vacuum solar heating device. The vacuum solar heating device is detachably mounted on an opening defined in the hollow body. The vacuum solar heating device has a transparent tube, a connecting collar and a solar energy absorber. The tube has a closed end, an open end and a vacuum chamber defined around the tube. The connecting collar is mounted on the open end of the tube and has an inner thread screwed onto an outer thread around the opening in the hollow body. The solar energy absorber is mounted in the tube to absorb solar energy. The solar energy absorber can be a heating rod with two solar energy-absorbing plates mounted on the heating rod, or a solar energy coating coated on the tube. With such a vacuum solar heating device, the liquid in the flask can be heated so the temperature of the liquid can be maintained for a desired long time.
Other objects, advantages and novel features of the invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings.